Abstract
Studies to determine the Michaelis constants (lc) and maximum reaction velocity (V„,„,) for urease activity in five soils (S-I, 5-2, 5-3, 5-4, 5-5) representing upland (5-2, S-3, S-4) and lowland (S-I, 5-5) cropping systems, were conducted under laboratory conditions. The upland soils were cropped to maize, cotton and sorghum and the lowland soils were cropped to flooded rice. The Michaelis constants (K„,) determined in upland soils ranged from 0.69 to 1.5 x 10-'M and those in lowland soils ranged from 5.4 to 8.7 x 10-W. The V„,„, values ranged from 230 to 500 ug urea N hydrolysed g' soil If' in upland soils and from 130 to 150 ug urea N hydrolysed g•' soil in lowland soils. The results showed that Michaelis constant (IC,,,) could be a sensitive indicator to measure and compare the urease activity of different soils.
A. Hamid, M. Yaqub , M. Ahmad. (1999) Michaelis constants of urease in alluvial alkaline soils under different cropping systems, The Journal Soil & Environment , Volume 16, Issue (1-2).
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